New Eruption May Be Brewing at El Hierro Volcano

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Two years after a new underwater volcano appeared offshore of El
Hierro in the Canary Islands, earthquake swarms and a sudden
change in height suggest a new eruption is brewing near the
island's villages, officials announced today (Dec. 27).

After the announcement, one of the largest temblors ever recorded
at the volcanic island, a magnitude-5.1 earthquake, struck
offshore of El Hierro at 12:46 p.m. ET (5:46 p.m. local time)
today, the National Geographic Institute reported. Residents on
the island reported strong shaking, and the quake was felt
throughout the Canary Islands, according to news reports. The
earthquake's epicenter was 9 miles (15 kilometers) deep.

Before the earthquake struck early this afternoon, the island's
volcano monitoring agency, Pelvolca, had raised the volcanic
eruption risk for
El Hierro to "yellow." This warning means that activity is
increasing at the volcano, but no eruption is imminent. A similar
burst of activity prompted a yellow warning in June 2012, but the
volcano soon quieted down.

Parts of El Hierro have swelled nearly 3 inches (7 centimeters)
in the past week, with the growth centered between El Pinar and
La Restinga, according to Involcan, the Volcanological Institute
of the Canaries.

More than 550 earthquakes rattled the island between Monday and
Wednesday, also centered on La Restinga. About 30 of the
earthquakes were greater than magnitude 3, Involcan said. The
earthquakes are triggered by magma rising underground, fracturing
rocks and swelling the surface as the hot rock reaches upward.
"The earthquake swarm corresponds to a new magmatic intrusion,"
Involcan said this morning in a statement.

Today's preliminary magnitude-5.1 earthquake was on the opposite
side of the island from the ongoing swarm.

El Hierro was the site of a spectacular underwater volcanic
eruption in 2011, which severely affected island fisheries
and forced islanders to evacuate.